The present invention relates to a method and a system for chilling of carcass parts after slaughter.
It is well known that during cooling of carcasses from the kill temperature to a temperature at which deterioration of the meat is substantially prevented, a fairly large volume of moisture may be lost from the carcasses. This moisture loss results in a loss of quality in the end product and a lower end weight of the product. A great deal of time and effort has therefore been expended to attempt to prevent moisture loss and meat deterioration.
One method taught in the prior art is known as crustfreezing, wherein the outermost layer of the carcass is frozen, thereby preventing a substantial amount of water loss. See for example, U.S. Pat. Nos. 4,028,774, 4,325,221 and 4,367,630. The main problem exhibited by crustfreezing is that it can result in color change, spoilage and/or freezer burn in the outer layers of the carcass. As can be seen, this method""s ability to decrease moisture loss is limited. U.S. Pat. No. 4,810,515 teaches a method comprising moving carcasses through a refrigeration chamber on a conveyor belt system. The temperature of the refrigeration chamber ranges from xe2x88x926xc2x0 C. to +3xc2x0 C. While on the conveyor belt, carcasses pass through from 10-50 xe2x80x9cmist cabinsxe2x80x9d wherein the carcasses are sprayed with very fine droplets of liquid. The heat of the carcasses evaporates the droplets from the surface, thereby creating a high humidity level around the carcasses. Once the droplets have evaporated, the carcasses encounter the next xe2x80x9cmist cabinxe2x80x9d. This evaporation and resulting humidity zone in turn prevents moisture loss.
PCT Application WO99/21429 teaches a method for chilling carcass parts comprised of submerging the carcass into a chilling medium, such as brine or slush ice. The carcass is enclosed in a foil or film prior to submersion in the chilling medium. Once removed from the chilling medium, the temperature of the carcass is allowed to equilibrate.
U.S. Pat. No. 4,940,599 teaches a method of chilling poultry carcasses comprised of subjecting carcasses to a cryogenic bath to lower the temperature of the carcass. Liquid is applied to the surface of the carcass either before or after the carcass is immersed in the cryogen, the end result being that freezing of the outermost layers of the carcass is prevented but an ice layer forms on the outer surface of the carcass. The carcass is then subjected to 10-15 minutes in a standard refrigeration chamber for further cooling, during which time the ice layer melts. As will be appreciated by one knowledgeable in the art, the thickness of the ice layer cannot be accurately controlled in this method, as the amount of moisture on the surface of the carcass will vary according to the delay between applying the liquid and subjecting the carcass to the supercold environment or removing the carcass from the supercold environment and applying the liquid.
U.S. Pat. No. 5,577,392 teaches a tunnel freezer for chicken carcasses which is comprised of spraying a cryogen such as liquid nitrogen or carbon dioxide snow directly onto the carcass as it travels through a tunnel having sufficient vortical flow therein such that the cryogen is circulated throughout the tunnel.
In some other methods, animal carcasses are chilled with cold air in an intensive process in which carcasses are suspended from gambrels and led through a chilling room while cold air is blown onto the carcasses. The intensive air chilling, also known as tunnel chilling, blast chilling or quick chilling, is distinguished by a low chilling loss and PSE-frequency. Specifically, this method comprises a first stage wherein the surface temperature of the carcass is lowered to near freezing by subjecting the carcass to a combination of low temperature and high wind velocity in order to prevent cell damage and deterioration of the carcass. The carcass then passes to a second stage wherein the temperature and conditions are more mild, which allows heat to be removed from the carcass while preventing the carcass from being xe2x80x9cshockedxe2x80x9d due to an abrupt temperature change. In the third zone, the conditions are even milder, allowing the carcass to recover from subjection to the supercold environment, prior to transfer to the traditional refrigeration unit. While this method produces adequate results in terms of preventing shrinkage and moisture loss while producing meat of good quality, improvements in the process can still be made. Clearly, an improved process for chilling carcasses wherein moisture loss is greatly reduced but high quality meat is obtained is needed.
The present invention is a method used during the processing of a carcass, in which it is subjected to a super cold, high air velocity environment (also known as xe2x80x9cQuick Chillxe2x80x9d or xe2x80x9cBlast Chillxe2x80x9d).
While still in this xe2x80x9cQuick Chillxe2x80x9denvironment, at a point where the surface temperature of the carcass is at near freezing, liquid is sprayed on the carcass, effectively snapping a controlled shell of ice onto the carcass. This is achieved by passing the carcass through one or more spray booths situated within the xe2x80x9cQuick Chill Tunnelxe2x80x9d. Each booth contains a plurality of spray nozzles, which may be of various sizes and spray patterns.
This method produces a superior quality of meat, while virtually eliminating yield loss.
According to a first aspect of the invention, there is provided a method of chilling a carcass in which moisture loss is substantially eliminated and quality of meat is maintained comprising:
subjecting a carcass to a super cold environment such that the surface temperature of the carcass approaches freezing; and
spraying a liquid onto the carcass such that the exterior and the cavity of the carcass are encased in ice, thereby preventing moisture loss and cell damage from the carcass.
The liquid may be water.
The liquid may be sprayed onto the carcass within the super cold environment.
The liquid may be sprayed onto the carcass by a plurality of nozzles substantially enclosed in a booth.
The thickness of the ice may be controlled.
The thickness of the ice may be controlled by the spray rate or by the quantity of liquid sprayed.
The liquid may be sprayed onto the carcass by a plurality of nozzles substantially enclosed in two or more booths.
Unless defined otherwise, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described.
As used herein, xe2x80x9cQuick Chill environmentxe2x80x9d or xe2x80x9csuper-cold environmentxe2x80x9d refers to an environment in which high velocity air is used to reduce the temperature of meat.
As will be seen, the present invention is described in connection with pork, but could be applied equally to other large carcass meats using the xe2x80x9cQuick Chillxe2x80x9d process of super cold, high velocity air.
Presently, the carcass is suspended from a gambrel and travels through a multistage xe2x80x9cQuick Chillxe2x80x9d environment, in which super cold, high velocity air used to reduce the temperature of the meat as quickly as possible. As well, in the present state, the carcass is sprayed prior to entering the xe2x80x9cQuick Chillxe2x80x9d environment, as is common practice in the industry.
Stage one of the xe2x80x9cQuick Chillxe2x80x9d environment is very intense in the refrigeration sense. Wind velocity combined with sensible temperature produces (watts) an environment wherein a crust forms on the surface of the carcass as quickly as possible. The quicker this is achieved, the less moisture is lost throughout the refrigeration process.
Stage two provides additional refrigeration effect in a less intense environment to help remove heat from the inside of the carcass but at the same time provides a gradual approach toward storage temperature condition, thereby reducing shock.
Stage three provides a gradual approach toward storage temperature conditions reducing shock which causes xe2x80x9cblack bonexe2x80x9d.
It is common knowledge that the use of the xe2x80x9cQuick Chillxe2x80x9d process as described generally above will at best result in a decrease of moisture loss to approximately one percent, but in doing so can also result in cell damage and a decrease in meat quality.
The present invention represents an improvement in the above-described method in that the carcass is sprayed with a liquid, for example, water, although other suitable liquids may also be used while within the super-cold environment.
Specifically, the carcass is brought into the first stage of the process on a gambrel. The combination of low temperature and high air currents act to reduce the surface temperature to near freezing. Once this occurs, and while still inside the xe2x80x9cQuick Chillxe2x80x9d environment, the carcass is passed through one or more spray booths, each containing a plurality of spray nozzles, wherein the exterior of the carcass as well as the exposed cavity are sprayed with a liquid. The applied liquid snaps an ice shell on all exposed surfaces of the carcass. As will be apparent to one knowledgeable in the art, the thickness of the shell can be controlled by changing the location of the spray booth or booths and by regulating the amount of liquid sprayed onto the carcass.
The result of the above process is a moisture loss of near zero percent, a greater heat release rate when lowering the internal temperature of the carcass, as well as significant improvements in color and meat quality. The ice shell is applied in the first stage, but remains on the carcass throughout the final stage, providing a more efficient heat transfer medium, while virtually eliminating moisture loss and maintaining a high quality of meat.
It is of note that in the above described embodiment, the carcass is not removed from the xe2x80x9cQuick Chillxe2x80x9d environment for spraying. Although it is possible to remove the carcass from the xe2x80x9cQuick Chillxe2x80x9d process for spraying, doing so would hinder the ability to effectively control the ice layer. However, it may be desirable in some embodiments to lower the temperature of the carcass to near-freezing by exposure to the super-cold environment and then remove the carcass from said environment to apply the liquid. As can be seen, in these embodiments, liquid would not necessarily have to be applied within a spray booth.
In some embodiments, the booth consists of sidewalls containing headers with spray nozzles in which the carcass passes through. It is configured in such a way that the entire carcass is sprayed with a liquid to encapsulate the carcass in an ice shell.
As discussed above, the basic xe2x80x9cQuick Chillxe2x80x9d process is known in the art and one example of the improved process is now described herein for illustrative purposes only. As will be appreciated by one knowledgeable in the art, the process will now be further described by way of example although the invention is not limited to the example. In addition, it is of note that the improvement described herein may be used in combination with other embodiments of xe2x80x9cQuick Chillxe2x80x9d methods.